“I am a life-long Republican because I believe in promoting freedom and limiting the reach of government,” Murkowski wrote.

“When government does act, I believe it should encourage family values. I support the right of all Americans to marry the person they love and choose because I believe doing so promotes both values: it keeps politicians out of the most private and personal aspects of peoples’ lives – while also encouraging more families to form and more adults to make a lifetime commitment to one another.”

The president of the Human Rights Campaign, a leading human rights organisation, commended the Alaskan Senator for coming out in support of equal marriage.

“We hope other fair-minded conservatives like Senator Murkowski stand up and join her,” HRC President Chad Griffin said in a statement.

“Alaska may be nicknamed ‘the Last Frontier,’ but we’ve got to make sure that LGBT Alaskans don’t have to wait to find justice.”

Murkowski previously described her views on equal marriage as “evolving”.